1. Field of the Invention
The present invention relates to a recording and reproducing apparatus for a non-erasable recording medium.
2. Description of the Prior Art
Non-erasable recording media, i.e., recording media to which data can be written but once written cannot be removed or overwritten, are used because of their large storage capacity for recording large amounts of information that does not require much modification after completion. Examples of such information include official public documents, standards, and master data files, encyclopedia, and databases that are recorded to CD-ROM. Regardless of how infrequent the need for revision may be, however, it is obvious that the very nature of information makes appending, modifying, and otherwise updating the information to the most up-to-date content extremely desirable. This is particularly true when using such media to distribute such documents as standards and encyclopedia.
However, when data that is different from the data that has already been recorded must be appended, the already-recorded data must be re-recorded together with the new data because data cannot be overwritten with non-erasable recording media, or non-erasable media. In other words, the same data is redundantly recorded to another location on the same non-erasable medium. This is also true when only part of the already-recorded data is modified in addition to re-recording the data that changed, the unchanged data is also redundantly re-recorded.
These types of non-erasable media include CD-R (Compact Disc Recordable) media that can be reproduced on CR-ROM drives conforming to the so-called Red Book standards for audio CDs and the Yellow Book standards for data CD-ROMs, and CD-WO (Compact Disc Write Once) media defined in the Orange Book.
The non-erasable CD-R medium is defined in the Orange Book, which also defines the CD-E (Compact Disc Erasable) and CD-RW (Compact Disc Rewritable) rewritable media standards whereby information can be recorded and erased or overwritten. A recording apparatus that uses a 300 mm diameter optical disc medium called a WORM (Write Once Read-only Memory) is also defined in IEC-13614. In addition to these non-erasable media based on the CD-ROM standard, there is DVD-R, which is based on DVD.
Note that the Red Book, Yellow Book, and Orange Book have been standardized by the International Electrotechnical Commission (IEC) as IEC-908, IEC-10149, and IEC-13490.
The structure and recording method of CD-R media are described briefly below with reference to FIG. 19, FIG. 20, and FIG. 21 as one example of non-erasable media. Note that to produce a CD-R disc that is reproducible on an existing CD-ROM drive it is necessary to satisfy the physical format specifications defined in the Yellow, Red, and Orange Books as well as the logical format defined in ISO-9660.
As shown in FIG. 19, a lead-in area 302 to which is recorded the lead-in information Li is formed near the inside circumference of the disc, and a lead-out area 306 is provided near the outermost circumference of the disc. The user-data area 304 used by the user for recording any user data UD is disposed between the lead-in area 302 and lead-out area 306. This is because a lead-out area must be recorded on the outside circumference side adjacent to the recorded user data; so that the lead-out information Lo can be recorded even if data is recorded to the full capacity of the user data UD, a lead-out area 306 not included in the user-data area 304 is reserved at the outside circumference of the CD-R disc.
If there is sufficient unrecorded space in the user-data area 304, the lead-out information Lo is recorded following the user data UD recorded to the user-data area 304, and a new lead-out area Lo is formed separately to the reserved lead-out area. Only when there is not sufficient space in the user-data area 304, e.g., only when the user-data area 304 is substantially completely used for user data UD recording, is the lead-out information Lo recorded to the reserved lead-out area 306.
In an audio CD the user-data area 304 is divided into tracks as the unit area to which the data for one selection is recorded. Division into track units is not necessary when recording computer data, however, and the user-data area 304 therefore normally consists of only one track. In other words, the user-data area 304 may comprise from 1 to 99 tracks. A table of contents (TOC) containing information relating to each track is recorded to both the lead-in area 302 and lead-out area 306.
To the inside circumference side of the lead-in area 302 is also formed a PMA (Program Memory Area) area 300 to which track information is recorded.
Each of these areas is recorded as a single data stream extending in a spiral pattern from the inside circumference to the outside circumference. Note also that a special information SP area 900 is also provided at a fixed position on the disc as shown in the figure. The SP area 900 stores the starting position of the PMA area, the starting position of the PCA area used for recording power tests, the disc capacity, and the disc capacity and other special information SP.
A typical illustration of the storage area of a CD-R disc showing the spiral data stream stretched into a straight line is shown in FIG. 20. As shown in FIG. 20, the user-data area 304 and the lead-in area and lead-out area containing the TOC for the user-data area 304 formed on a single disc constitute one session S. In addition, a session in which the lead-in area and lead-out area are the reserved lead-in area 302 and lead-out area 306 is also called a session 308.
A CD-ROM drive reads the TOC information from the lead-in area 302 (Li) or the lead-out area 306 (Lo), or both, to obtain the track information for the disc. The user data UD is recorded as a track to the user data area, and for the reasons described above the lead-in information Li and lead-out information Lo must be recorded before and after, respectively recording the lead-in area and lead-out area to complete a session.
However, when the user data that is actually recorded is smaller than the recording capacity of the reserved user data recording area 306, the lead-out area Lo is recorded inside the user-data area 304 shown in FIG. 19, i.e., is recorded to the inside circumference side of the lead-out area 306, because the lead-out information Lo must be recorded contiguously from the end of the user data.
Recording media such as the CD-R disc in which one session S is formed per recording side are therefore called "single session" media. Note that in this case nothing is recorded to the reserved lead-out area 306.
It is also possible to record a new session to the blank part of the user-data area 304 and record separate user data to this new session. It is thus possible to form plural sessions S in the user-data area 304 insofar as capacity permits. Note, however, that there is a maximum limit of 99 tracks. Because each session S must contain at least one track, the maximum number of sessions S is also 99. However, capacity limitations mean that the maximum actual number of sessions possible is about 40. There are also only 100 Power Calibration Areas (PCA) available for use before recording. Because laser power adjustment is not always necessary, however, there is no upper limit on the number of packet recordings.
Media on which plural sessions are thus formed and recorded are called "multi-session" media.
The data stream of a multi-session recording medium is shown in FIG. 21 stretched into a straight line as in FIG. 20. In this example two sessions S1 and S2 are recorded to one CD-R disc. The entire first session S1, including the lead-in area Li1 302, the user data area UD1, and lead-out area Lo1, and the lead-in area Li2 and user data area UD2 of the second session S2, are recorded to the user-data area 304 shown in FIG. 20.
The reserved lead-in area 302 is used for the lead-in area Li1 of the first session S1, and the reserved lead-out area 306 is used for the lead-out area LO2 of the second session S2. As described above, however, more than two sessions can be formed, and the lead-out area Lo of the final session can obviously be formed separately from the reserved lead-out area 306.
One method of recording plural times to a non-erasable optical CD-R disc is to record a complete session conforming to the ISO-9660 format as described above. This method of recording by forming plural sessions on a single CD-R disc is called "multi-session recording." One method of reading data from a multi-session recorded disc is the Photo CD method.
Note that the method of recording by forming a single session on a single CD-R disc is called "single session recording."
To record without forming sessions it is necessary to use a logical format other than ISO-9660. One such format is the ECMA168 format standardized by the European Computer Manufacturers Association (ECMA).
As described with reference to FIG. 19, FIG. 20, and FIG. 21 it is possible with a CD-R disc to record the lead-in area and lead-out area to the disc after recording the user data to a specific track on the disc to complete a session. To accomplish this the PMA is used to store the track information until the session is completed. The PMA is a reserved area near the innermost circumference of the disc for storing the track information. By recording the track information to the PMA each time a track is recorded on the disc, it is possible to manage what data is recorded to what part of the track on the disc.
It is also possible to keep a particular part of the user data area blank by recording to the PMA the track information for tracks to which no data is actually written. This process of holding a particular area of the track is called "reserving" a track, and a disc area to which no data is actually recorded but for which the track information is recorded to the PMA is called a "reserved track."
By thus appropriately writing track information to the PMA, it is possible to manage the tracks in the recording area of the disc as recorded tracks, the next tracks to be recorded, i.e., blank user data area, and reserved tracks.
Note that the track information contains the disc ID, copy information indicating whether data duplication is permitted, the physical format, track numbers, and track starting positions. In addition to the track information, the PMA also contains track end point information.
Except for the lead-in area and lead-out area, the CD-R disc must conventionally be recorded without interruptions in the data from the inside circumference to the outside circumference of the disc, i.e., through the user data area. However, it is also possible by reserving a track to keep a blank user data area on the inside circumference side of the recorded area of the disc. Data can be recorded to this reserved track at any time before a session is created. The TOC is also redundantly recorded to the lead-in area and the lead-out area.
ISO-9660, which defines the logical format of a CD-ROM, specifies that a Primary Volume Descriptor (PVD) area be recorded to sector 17 from the beginning of the user data area of a session. Sectors 0-15 are reserved as a system area, the use of which is not defined by ISO-9660. The address of the table managing information about the files recorded to the disc is recorded to the PVD.
The structure of the PVD in a single session medium is shown in FIG. 22. The PVD contains the size of the volume space VPS (Volume Space Size), the size of the path table PTS (Path Table Size), the path table location LPT (Location of Path Table), and the directory record RED (Root Directory Entry) for the root directory.
The path table PT contains, as shown in FIG. 22, the Length of Directory Identifier, Extended Attribute Record length, Location of Extent, Parent Directory Number, and Identifier information.
The Root Directory Record RDI contains the Length of Directory Record, Extended Record Length, Location of Extent, Data Length, date, File Flags, File Unit Size, Volume Sequence Number, Length of File Identifier, and the File Identifier information. These elements cannot be generated before or after recording, and must be stored simultaneously to recording the data and file.
The file name, file size, and other file information can be obtained by tracing the Directory Record DI, which is a reference tree of all files and directories. This Directory Record DI contains information about all subdirectories and files in the directory. The disc directory is referenced to access a particular file on a CD-ROM or CD-R disc. More specifically, the Directory Record DI, which is a directory information recorded on the disc, must be read to obtain the address recorded for the desired information. In other words, to reproduce the file storing the contents of the disc after recording, the information that must be contained in the Directory Record DI must be stored with the data.
The Path Table PT has been defined as a means of compensating for the slow access speed of CD-ROMs and the characteristics of CD-R discs. This means that to access directories .Yen.111.Yen.222.Yen. . . . .Yen.999, nine seek and reproduce operations are needed to trace the Directory Record DI from the root. Because both seeking and reading are slow with a CD-ROM, a Path Table PT is provided to compile the directory records for all directories into a table that can be referenced to directly obtain the location of the target directory record. As a result, the overall table size is variable until it is decided that no more data will be recorded, at which time it is first possible to fix the user data content to be recorded to the Path Table PT. The table address must, however, be stored to the PVD.
Neither the Root Directory Record RDI nor the Path Table PT can be generated until the data files recorded to the disc and the directories are fixed. As a result, the PVD can also only be generated after the PVD information for the session shown by way of example in FIG. 22 is fixed.
However, the PVD must be recorded to a fixed position according to the ISO-9660 standard, specifically to sector 17 from the beginning of the user data area immediately following the lead-in area. It is therefore not possible to record the PVD to disc until all user data to be recorded for a session is fixed. This means that one recording to the disc must be one session where "one recording" is defined as from the beginning to the end of one recording operation by the recording apparatus to the non-erasable media based on a user command. One recording is therefore unrelated to the number of recorded files and size, and is also unrelated to the number of laser emissions to the disc. It is possible to append the user-data area 304 after the PVD is recorded, but the appended data will not be contained in the logical format expressed by the PVD, and the appended data can therefore not be read as a file.
In other words, once recording to a CD-R disc has begun, it is necessary to finish recording to the end to complete a session. It is not possible to interrupt recording, use the CD-R disc, and then at a later date finish recording the rest of the interrupted recording or record new data. It should be noted, however, that the lead-in area and lead-out area can be generated from the PMA, and can therefore be recorded after recording is ended.
The arrangement of the recording area in a Photo CD format CD-R disc after once appending to the recording area as shown in FIG. 21 is shown in FIG. 23 for a disc recorded with the packet writing method defined in the Orange Book. As described with reference to FIG. 22, the first session S1 contains following the lead-in area Li1 a Primary Volume Descriptor PVD1 storing the address of the table managing the information for the file F1 recorded in this session to user data UD1. Format information Fi1 describing the directory structure and the user data file F1 (UD1) is recorded between PVD1 and user data area UD1. The second session S2 likewise contains lead-in area Li2, PVD2, format information Fi2, user data UD2 (file F2), and lead-out area Lo2.
However, because format information Fi2 contains information for both user data UD1 (F1) and user data UD2 (F2), lead-in area Li1, PVD1, format information Fi1, and lead-out area Lo1 are invalid areas never used by the CD-ROM drive. For descriptive convenience the sizes of the lead-in areas and lead-out areas are not shown accurately in the figure. In practice, however, the lead-in area Li is from 10-25 megabytes (MB), and the lead-out area Lo is 5-15 MB, large in comparison to the normal file size, and the majority of the disc is consumed by information other than the actual files.
The arrangement of the recording area in a Photo CD format CD-R disc after once appending to the recording area as shown in FIG. 21 is shown in FIG. 23 for a disc recorded with the track-at-once method defined in the Orange Book. As described with reference to FIG. 22, the first session S1 contains following the lead-in area Li1 a Primary Volume Descriptor PVD1 storing the address of the table managing the information for the file F1 recorded in this session. Format information Fi1 describing the directory structure and the user data file F1 (UD1) is recorded between PVD1 and user data area F1 (UD1). The second session S2 likewise contains lead-in area Li2, PVD2, format information Fi2, user data F2 (UD2), and lead-out area Lo2.
As with multi-session recording using the packet writing method shown in FIG. 23, the majority of the disc is consumed by information other than the actual files.
It is thus necessary with Photo CD format multi-session recording to complete a session and also record a TOC area separately from the recorded data. This means that in addition to the extra processing time required for session formation and TOC recording, significant recording capacity equal to approximately 2% to 6% of the disc capacity is consumed outside the data area each time data is appended.
In addition, when a disc recorded with plural sessions is accessed on a CD-ROM drive that is not compatible with multi-session Photo CD discs, the drivers firmware can only read the first session, and it is not possible to reproduce the second and subsequent appended sessions.
Furthermore, even with drives that can reproduce discs containing plural sessions, there is a noticeable delay resulting from processing after the disc is inserted. A logical format standard in which sessions are not formed cannot be used with software, including drivers and utilities, implementing the existing CD-ROM file system.
Moreover, as a general problem with non-erasable media, even when data separate from the already-recorded data is newly appended and recorded, the same data must be redundantly recorded to a separate location on the same non-erasable media. This means that the utilization efficiency of the medium's recording area is significantly impaired.
Therefore, in consideration of the aforementioned problems of the prior art, an object of the present invention is to provide a recording and reproducing apparatus for non-erasable media capable of resolving or significantly reducing the problems of redundantly recording the same data when appending data to a non-erasable medium, and to thereby improve the utilization efficiency of the recording area, and which is more specifically capable of shortening recording time, conserving recording capacity, shortening the startup time during recording and reproduction, and enabling reproduction on a single session compatible drive.